Emergency brake systems of the general type under consideration are used in commercial vehicles to effect a brake application upon detection of an imminent collision with an object. The term “collision” means an impact of the vehicle with the object, which can be moving, such as another vehicle that is traveling ahead of the vehicle, or stationary, such as a road sign or a non-moving vehicle.
In order to assess whether the vehicle is on a collision course with an object, once the object is determined to be in the environment of the vehicle, the future driving behavior of the vehicle with regard to the object is determined, In so doing, consideration is given to the dynamic parameters of the vehicle and also of the object, including whether the vehicle can still avoid the object or whether an impact can be prevented by means of a brake application, in other words whether the driver can theoretically still prevent the collision. If the driver is no longer able to prevent a collision, an emergency brake application is performed automatically.
A brake system of this general type is described in DE 10 2010 006 214 A1. Once an object is detected in the environment of the vehicle, the last possible moment to intervene for a brake application is determined by taking into consideration the prevailing dynamics of the vehicle and the object and also the reaction time of the driver. Based thereon, a brake application is initiated in order to prevent a collision and to reduce the consequences of a collision. Furthermore, the last possible moment for avoiding a collision is taken into consideration by assuming that the avoidance trajectory of the vehicle corresponds to a parabola or a circle.
EP 1 057 159 B1 describes a method for preventing a collision, wherein a calculation is performed to determine a minimum distance that is required with respect to a vehicle ahead in order at a maximal possible vehicle deceleration to avoid a collision with the vehicle ahead. The relative velocity and the relative acceleration between the two vehicles are taken into consideration. Furthermore, a minimal distance is also taken into consideration that is required for a possible avoidance maneuver (steering the vehicle past the vehicle ahead).
With reference to these two distances, an emergency brake application is initiated in the event of a possible collision.